Impelling and pulse control system for electronic pendulum clocks



June 19, 1962 R. w. REICH IMPELLING AND PULSE CONTROL SYSTEM FOR ELECTRONIC PENDULUM CLOCKS Filed April 9, 1958 m m M ROBERT WALTER RE/Ch' ATTORNEYS the bias of the transistor.

United States Patent 3,040,225 IMPELLING AND PULSE CONTROL SYSTEM FOR ELECTRQNIC PENDULUlVI CLOCKS Robert Walter Reich, Freihurg im Breisgau, Germany,

assignor to Jahresuhren-Fabrik G.m-.b.H., Aug. Schatz & Sohne, Triberg, Black Forest, Germany Filed Apr. 9, 1958, Ser. No. 727,293 Claims priority, application Germany Apr. 10, 1957 6 Claims. (Cl. 318-132) The present invention relates to electronic clocks. More in particular, the present invention relates to an 'impelling and pulse control system for the pendulum in electronic clocks.

It is known in the art to provide electronic clocks with an impelling system comprising a transistor and a driving coil. These known clocks operate with a pendulum carrying permanent magnets at both ends thereof. The driving coil is provided in the emitter or in the collector circuit of the transistor and an exciting coil controls As soon as the pendulum leaves the exciting coil the permanent magnet, produces an induction current having negative polarity with respect to the direction of the base current of the transistor.

These clocks have the disadvantage that the pendulum in these clocks actually oscillates freely and the driving impulses applied thereto merely supply new energy to I keep up the natural frequency of the pendulum. Thus,

fully mechanically operated pendulum clocks. An additional inaccuracy may results from changes of the voltage from the power source which changes occur as a matter of time whenever dry cell batteries or accumulators are used, or which are inevitable it the current is obtained from the mains. Since the intensity and duration of the driving pulse depends on the voltage supplied by the power source, a change of the latter will result in the clock running inaccurately. In addition, the accuracy is still further reduced by the characteristics of the transistor varying with temperature. The ambient temperature may vary by or- Centigrade and more and thus alter considerably the operation of the transistor. An increase of temperature by 20 will multiply the temperature-dependent current of the transistor by 10 and more. Since the intensity and duration of' the negative pulse produced by the magnet entering or leaving the exciting coil will not changewith the speed of the pendulum being constantand since the base current will vary with a rise or decline of temperature, theresulting effective base current will vary with the temperature thereby indirectly influencing the intensity and duration of the 'driving pulse, and a further inaccuracy of the pendulum and the clock will result.

It is an object of the present invention to provide a new and improved impelling and pulse control system for electronic clocks, which operates fully automatically and guarantees a very accurate operation of the clock.

I It is another object of the present invention to provide an impelling and pulse control system for electronic clocks, whereby the pendulum is impelled twice during each cycle and each pulse is a controlled one.

It is a further object of the present invention to provide an impelling and pulse control system for electronic clocks,

3,040,225 Patented June 19, 1962 ice which is substantially independent from changes in temper-ature and variations of the voltage supplied from the power source.

These objects are achieved by the automaticimpelling and pulse controlling system for electronic pendulum clocks of the present invention in which both ends of the pendulum carry a short permanent magnet and which comprises a pair of coils disposed at the end of each oscillatory movement of the pendulum and each comprising a high ohmic exciting coil and a low ohmic driving coil, and wherein the exciting coils produce a pulse of predetermined polarity at the base of a transistor whenever the magnets leave and/or enter the coils, thereby supplying a pulse to the driving coil connected to the emitter circuit of the transistor, thus producing a driving impulse in the required direction, and further comprising highly blocking diodes disposed in the circuit formed by the exciting coils and the base of the transistor, which diodes block any braking driving impulse.

The present invention is illustrated in the accompanying drawings, wherein:

FIGURE 1 is a side elevational View, partly in section of the pendulum of an electronic clock with the drive and control means of the present invention;

FIGURE 2 is a side elevational view, partly in section,

of a rotary pendulum of another electronic clock with the drive and control means of the present invention.

' The swinging penduluml has, a governor weight 2 and .a tube 1a which is provided with two permanent magnets 3 and 4'disposed at opposite ends thereof; two pairs of coils 6, 7 and 8, 9 are magnetically coupled with the 'permanentmagnets, respectively. Coils 6 and 8 are driver coils, and coils 7 and 9 are exciter coils. The 'two driver coils 6'and 8 are connected in parallel, and they are connected between the emitter of transistor 10 and the positive terminal of a voltage source. The two exciter coils 7 and 9 are also connected in parallel, and they are further connected across the base-emitter part of transistor 10. In the thus defined base circuit there are provided highly blocking diodes 11, 12, and 13, and between the collector and the base of the transistor 10 there is provided a potentiometer resistor 14.

The collector of transistor 10 is connected to the negative terminal of the voltage source.

In the swinging pendulum clock as illustrated in FIG- URE l the coils are wound upon bobbins. Each bobbin has a clearance sufiicient to permit the pendulum and the permanent magnet to pass therethrough.

The device as outlined above operates as follows:

Assuming the pendulum is in the position as shown in the drawing, magnet 3 is just entering coil combination 6, 7 and particularly exciter coil 7 thereof. A voltage is induced in this coil 7. Suppose the voltage is directed so as to generate a current which would flow to the base of transistor 10, such current is prevented by diodes 11 and 12, and the voltage in coil 7 thus remains substantially ineifective. The pendulum continues to move toward the left, reaches the apex and returns towards the right. This'return movement induces in coil 7 a voltage opposite to the one induced before, and a base current is drawn from a transistor 10. The emitter-collector path of .transistorlll is thus opened whereby the current is permitted to flow through driver coils 6 and 8. Inasmuch as magnet 4 is still remote from the coils 9 and 8, the current in coil 8 remains ineffective. However, the current in coil 6 produces a magnetic field which repels magnet 3 and thus reinforces a movement to the right of the pendulum.

During the rightward movement of the pendulum, magnet 4enters coil 9 but nothing happens due to the blocking action of diodes 12 and 13. However, upon return by leftward'movement, magnet 4 induces a voltage in coil 3 9 of such polarity that transistor 10 opens, and a current is permitted to flow to coil 8 producing a repelling magnetic field reenforcing the leftward movement of the pendulum. Upon continuing movement to the left the cycle is repeated.

Since the direction of winding of exciter and driving coils may be a reversed one, the polarity of the voltage induced in'the exciter coils may also be reversed one. In this case the exciter coils produce pulses opening the transistor, and the driver coils produce attracting pulses when the respective magnets move into their associated coil combination, whereby reenforcement of movement operates so as to pull the pendulum more into the respective coil combination.

Alternatively one of the coil combinations may be arranged as to reenforce pendulum movement by way of pulling while the other coil combination reenforces pendulum movement by way of pushing.

FIGURE 2 shows the control and drive means of the invention as applied to a clock having a rotary pendulum. The rotary pendulum carries magnets 3 and 4 cooperating with two exciting coils 16 and 17 connected in series circuit connection and having a function connected to the emitter of transistor 10. The diodes 11, 12, 13 and potentiometer resistor 14 are connected to the base. There is one driving coil 18 connected across the base emitter path of the transistor 10.

In the rotary pendulum clock as shown in FIGURE 2, the driving coil 18 is arranged in the dead angle of rotation of the pendulum whereas the exciting coils 16 and 17 are so disposed that they are reached in the last third of each clockwise or counterclockwise rotation.

In the circuits shown, the exciting coils are connected to the transistor so that currents are induced in both coils whenever the pole of the permanent magnet at the outermost end of the pendulum leaves the associatedexciting coil and the permanent magnet on the other side of the pendulum enters the associated exciting coil. These induction currents in both coils result in a negative pulse with reference to the direction of flow at the base of the transistor. eifective pole of themagnet in combination with the sense of winding with the associated exciting coil can be so chosen that the pulses from the exciting coils reinforce each other. The highly blocking diodes inserted in each one of the exciter coil circuits provide for a compensation of temperature of the transistor. For this purpose, the driving coil or the driving coils which are connected in parallel or in series, and which are inserted into the collector-emitter circuit serve also as an ohmic resistance. A resistance combination is connected to the base as a voltage divider. The exciting coils serve as ohmic resistances between the emitter and the base of the transistor. between collector and base of the transistor, which resistor is so dimensioned that the leakage currents at base and collector are kept as small as possible. Since the bias voltage at the base is predetermined by this voltage divider, and since a corresponding resistance is provided in the emitter circuit, a complete temperature compensation is accomplished. The provision of the blocking diodes particularly of diode 12 is necessary as the bias voltage of the base could make effective at least a part of the positive pulses before the blocking effect of the transistor itself sets in.

Due to this arrangement, the pendulum is impelled during each swinging or rotary motion and there is no free swinging motion of the pendulum. For example, upon leaving one coil, automatically a driving pulse is produced and the pendulum is thereby pushed or drawn towards and into the other coil. The accuracy of the pendulum and the clock therefore depends on the magnetic control and the electronic switching arrangement of the invention. Length and weight of the pendulum determines the order of magnitude of its frequency within wide By employing short permanent magnets the An adjustable high-ohmic resistor is connected.

limits. For a given length of a pendulum and a given tronic impelling system will keep the number of oscilla tions constant. In clocks having a rotary pendulum with an angle of rotation of more than 200 it will be of advantage to choose the direction of flow of the current of the drive coils in such a manner that the pendulum is repelled rather than attracted. For this purpose preferably disk-shaped permanent magnets are employed inducing with their respective poles the negative pulse in the excit ing coil; the resulting driving pulse then repels the pendulum from the driving coil.

Any blocking forces are eliminated by the highly block ing diodes and there will be no braking effect applied to the pendulum or rotary pendulum. The pulses can be produced either as soon as the pendulum leaves the coil or as soon as it enters the coil independently from one another in such a manner that both exciting pulses rein- I force each other; this is due to the provision of two sepa rate magnets. 4

The main controlling power source in the impelling and pulse controlling system according to the invention is supplied by the moving permanent magnets having a very high coercive force, such as, for example, ferr'oxdure, alnico, ticonal, reco or similar magnets. The current sup= plied from the separate current source is still very small and in the order of one milli-arn-pere since the driving coil has to produce only a magnetic field attracting or repelling the permanent magnet. Due to the complete compensa-' tion of temperature the transistor leakage current is inde-' pendent from the temperature and amounts to a few mill amperes only. The life-time of the power source, for example a dry cell battery, is therefore extremely long and the time of operation of clocks equipped with such dry cell batteries is limited only by the natural exhaustion of the battery. Instead of dry cell batteries, very small accumulators, e.g. acorn cells, can be used. The charging means for these accumulators can be provided within the clock casing, and the clock is charged by connecting the charging means with the mains by an ordinary wire.

In very small watches the driving system preferably consists of a quarter segment which is provided with a conventional jewel bearing. The segment carries the nee essary permanent magnets having a correspondingly small size. The small coils associated with the permanent magnets are disposed in the same manner as in the swinging pendulum or rotary pendulum clock, as shown in FIG= URES l and 2. Since the impelling forces are very small, an extremely small transistor is sufficient. The operating transistor current is in the order of afraction of one milli-ampere, and the capacity of a miniature cell will supply the necessary energy to impel the clock over a long period of time.

Due to the double control action during one cycle of the pendulum, and due to the corresponding dual driving effect, the originally free oscillation of the pendulum is converted into a controlled oscillation, the accuracy thereof depending only on the electronic impelling system. The weight and the length of the pendulum originally determines the amplitude and frequency of the pendulum. Once this has been done, the accuracy thereof is entirely automatically controlled by the magnetic control and electronic impelling system of the invention. The accuracy can be adjusted at will be the voltage dividing ratio of the resistances at the base of the transistor. Since the resistance of the coil is fixed and cannot be changed this adjustment is preferably done by changing the potentiometer resistor between the base and the collector of the transistor.

It will be understood that this invention is susceptible the scope of the appended claims.

What I claim is:

1. An. impelling and pulse controlling system for electronic pendulum clocks, comprising, in combination, a current source, a transistor, two short, permanent magnets each having "a north and a south pole and being mounted at opposite ends of the pendulum of the clock, two highohmic exci-ter coils disposed in the areas reached by said permanent magnets at substantially the end of each oscillation of the pendulum, said exoiter coils being connected to the control circuit of said transistor two diodes, connected in series with said exciter coils, respectively, at least one low-ohmic driving coil connected to the collector-emitter circuit of said transistor, said exciting coils in cooperation with said diodes producing uni-directional pulses at the base of said transistor, thus causing in said driving coil a driving pulse impelling the pendulum whenever said permanent magnets move in such direction that the movement is re-inforced by said driving pulse, and at- .least one additional, highly blocking 'diode provided in the circuit formed by said exciting coils and the base of said transistor, said diodes blocking all driving pulses tending to brake the oscillatory motion of the pendulum.

2. An impelling and pulse controlling system for elec 'tronic pendulum clocks as described in claim 1, with the polarity of said permanent magnets being so disposed that one of said permanent magnets entering one of said coil combinations produces a negative impulse causing the driving pulse to be produced at the same side of the pendulum bearing said entering magnet.

3. An impelling and pulse controlling system for elec- :tronic pendulum clocks as described in claim 1, with the polarity of said permanent magnets being so disposed that one of said permanent magnets leaving one of said coil combinations produces a. negative pulse causing the driving pulse to be produced at the opposite side of the pendulum bearing said leaving magnet.

4. An impelling and pulse controlling system for electronic clocks comprising a rotary pendulum, a driving coil disposed at the extreme end of the arc of rotation of said rotary pendulum, and two exciting coils alternately energized by said pendulum and correspondingly controlling said driving coil.

5. An impelling and pulse controlling system for electronic pendulum clocks as described in claim 1, with temperaturecompensating means comprising as ohmic resistance means said driving coils connected to the emitter circuit of said transistor, as further ohmic resistance means said exciting coils disposed between theemitter and base of said transistor, and an adjustable ohmic resistor disposed between the collector and base of said transistor simultaneously controlling the accuracy of the clock.

6. An impelling and pulse controlling system for electronic pendulum clocks as described in claim 1, comprising a small accumulator as a power source, and recharging means for recharging said accumulator.

References Cited in the file of this patent UNITED STATES PATENTS 2,769,946 Brailsford Nov. 6, 1956 2,843,742 Cluwen July 15, 1958 2,877,399 Shaull Mar. 10, 1959 FOREIGN PATENTS 1,090,564 France Oct. 20, 1954 

